Anti-glare film

ABSTRACT

An anti-glare film is attached on a surface of a display, and includes an anti-glare layer. The anti-glare layer is set to have a sparkle value falling within a range from 6 to 10, which is defined based on a value of a standard deviation of luminance distribution of the display under a state in which the anti-glare film is attached on the surface of the display, a value of specular gloss of 30% or less, which is measured with 60-degree specular gloss, a value of transmission image clarity of 60% or less, which has an optical comb of 0.5 mm, and a haze value of 50% or less. Consequently, satisfactory anti-glare property can be provided while appropriately suppressing sparkle on the display.

CROSS-CITE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 16/618,530filed Dec. 2, 2019 know U.S. Pat. No. 11,650,357 issued May 16, 2023),which is the National Phase of PCT International Application No.PC/JP2018/023953, filed Jun. 25, 2018, which claims priority under 35U.S.C. § 119(a) to Patent Application No. 2017-151463, filed in Japan onAug. 4, 2017, all of which are hereby expressly incorporated byreference into the present application.

TECHNICAL FIELD

The present invention relates to an anti-glare film that preventsexternal light from reflecting on a display surface.

BACKGROUND ART

An anti-glare film is, for example, a film having a roughened surface onwhich recesses and protrusions are formed. The anti-glare film isattached on a surface of a display, and prevents external light fromreflecting on a display by scattering the external light.

Examples of a method of forming recesses and protrusions on the surfaceof the anti-glare film include a method of dispersing fine particles(filler) in a matrix resin (hereinafter, referred to as a fine particledispersion method) as disclosed in Patent Document 1, a method ofutilizing a phase separation structure formed from a liquid phase of aplurality of polymers by spinodal decomposition (hereinafter, referredto as a phase separation method) as disclosed in Patent Document 2, amethod of transferring and molding an irregular shape with a die(hereinafter, referred to as a transfer molding method) as disclosed inPatent Document 3, and the like.

CITATION LIST Patent Document

-   Patent Document 1: JP 2009-109702 A-   Patent Document 2: JP 3559505 B-   Patent Document 3: JP 2014-102356 A-   Patent Document 4: JP 2012-231496

SUMMARY OF INVENTION Technical Problem

When the anti-glare film is attached on the surface of the display,external light is prevented from reflecting on the display. However,display performance of the display through the anti-glare film isdegraded in some cases.

Particularly, in a case where the anti-glare film is attached on asurface of a display with high resolution pixels or the like, sparkle iscaused when light transmitting from the display through the anti-glarefilm is refracted on the recesses and protrusions on the surface of theanti-glare film or when the pixels of the display are magnified andvisually recognized due to a lens effect of the recesses and protrusionson the surface of the anti-glare film. As a result, an image is hard tobe visually recognized.

As a method of suppressing sparkle, for example, it is conceivable toreduce the recesses and protrusions on the surface of the anti-glarefilm. However, when the recesses and protrusions on the surface of theanti-glare film are reduced, there may be a risk of degradation ofanti-glare property.

In view of this, the present invention has an object to provide ananti-glare film having satisfactory anti-glare property whileappropriately suppressing sparkle on a display.

Solution to Problem

An anti-glare film according to an embodiment of the present inventionis attached on a surface of a display, and includes an anti-glare layer.The anti-glare layer is set to have a sparkle value falling within arange of from 6 to 10, which is defined based on a value of a standarddeviation of luminance distribution of the display under a state inwhich the anti-glare film is attached on the surface of the display, avalue of specular gloss of 30% or less, which is measured with 60-degreespecular gloss, a value of transmission image clarity of 60% or less,which has an optical comb of 0.5 mm, and a haze value of 50% or less.

Here, the sparkle value is a value being an objective indicator capableof evaluating sparkle on the display quantitatively. Specifically, thesparkle value is a value defined based on a value of a standarddeviation of the luminance distribution of the display, and indicates anextent of distribution of bright spots on the display.

Further, each of a haze value and transmissive clarity is a valuerelating to quality of anti-glare property. A relationship in which alarger haze value indicates higher anti-glare property, and lesstransmissive clarity indicates higher anti-glare property isestablished. However, when the haze value is excessively large, lightfrom a light source is scattered at a wide angle, which causes a problemof unsharpness of a character.

For example, when the anti-glare layer is formed by the phase separationmethod, the sparkle value, the specular gloss, the transmission imageclarity, and the haze value are achieved by adjusting kinds of phaseseparation materials to be combined, a heating temperature forcomposition in a drying process, a flow rate of a drying air caused toblow against the composition, or a linear speed during manufacturing.Further, for example, when the anti-glare layer is formed by the fineparticle dispersion method, the anti-glare layer is achieved byadjusting a difference between the refractive index of the matrix resinand the refractive index of the plurality of fine particles dispersed inthe matrix resin to fall within a predetermined range duringmanufacturing. Further, a difference in refractive indexes of the matrixresin and the fine particles falls within a predetermined range byselecting materials of the two having a predetermined refractive indexdifference and adjusting a shape of the fine particle, the number anddensity of the fine particles included in the matrix resin, and thelike. Moreover, a value of a ratio G2/G1 of a weight G1 of the matrixresin and a total weight G2 of the plurality of fine particles isadjusted.

According to the above-mentioned configuration, the anti-glare layer hasa sparkle value falling within a range from 6 to 10, and hence can beset while suppressing sparkle effectively based on the quantitativeevaluation.

Further, the Anti-Glare Layer is Set to have

-   -   a haze value of 50% or less and a value of the transmission        image clarity of 60% or less. Thus, high anti-glare property can        be achieved while generation of unsharpness of a character is        suppressed.

Moreover, the specular gloss measured with 60-degree specular gloss isset to a value falling within a range of 30% or less, which is a smallvalue, and hence reflection of external light can be suppressed.

Thus, the anti-glare film according to an embodiment of the presentinvention exerts an effect of having satisfactory anti-glare propertywhile appropriately suppressing sparkle on a display.

Further, in the above-mentioned configuration of the anti-glare filmaccording to an embodiment of the present invention, the anti-glarelayer may include a plurality of resin components, and a co-continuousphase structure formed by phase separation of the plurality of resincomponents may be provided.

Further, in the above-mentioned configuration of the anti-glare filmaccording to an embodiment of the present invention, the anti-glarelayer may include a matrix resin and a plurality of fine particlesdispersed in the matrix resin, and a difference of refractive indexes ofthe plurality of fine particles and the matrix resin may fall within arange from 0 to 0.07.

As described above, a difference in refractive indexes of the matrixresin and the fine particles is set within a predetermined range, andthe plurality of fine particles are dispersed in the matrix resin.Consequently, satisfactory anti-glare property can be provided whileappropriately suppressing sparkle on the display.

Further, in the above-mentioned configuration of the anti-glare filmaccording to an embodiment of the present invention, a ratio G2/G1 of aweight G1 of the matrix resin of the anti-glare layer and a total weightG2 of the plurality of fine particles included in the anti-glare layermay be a value falling within a range from 0.02 to 0.15.

Consequently, the anti-glare film including the anti-glare layer havinga structure in which the plurality of fine particles are dispersed inthe matrix resin can be manufactured satisfactorily.

Advantageous Effects of Invention

The present invention is configured as described above, and theanti-glare film exerts an effect of having satisfactory anti-glareproperty while appropriately suppressing sparkle on a display.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view illustrating a configuration of ananti-glare film according to an embodiment of the present invention.

FIG. 2 is a view illustrating a method of manufacturing an anti-glarefilm according to a third embodiment.

FIG. 3 is a view illustrating one example of a schematic configurationof a sparkle measurement apparatus according to an embodiment of thepresent invention.

DESCRIPTION OF EMBODIMENTS

With reference to the drawings, embodiments of the present invention aredescribed. FIG. 1 is a cross-sectional view illustrating a configurationof an anti-glare film 1 according to an embodiment of the presentinvention. The anti-glare film 1 is attached on a surface of a display16 a of a display device 16 (see FIG. 3 ). The anti-glare film 1includes a substrate film 2, an anti-glare layer 3, and an adhesivelayer 4.

The substrate film 2 is arranged between the surface of the display 16 aand the anti-glare layer 3, and supports the anti-glare layer 3. Theadhesive layer 4 is arranged between the surface of the display 16 a andthe substrate film 2, and fixes the anti-glare film 1 to the surface ofthe display 16 a.

The anti-glare layer 3 is formed on at least one surface of thesubstrate film 2. The anti-glare layer 3 provides anti-glare property tothe anti-glare film 1, and prevents external light from reflecting onthe display 16 a by causing the external light to scatter andreflecting. The anti-glare layer 3 also functions as a hard coat (HC)layer that covers the surface of the substrate film 2. As an example,the anti-glare layer 3 includes a plurality of phase-separable resincomponents.

The anti-glare layer 3 is set to have a sparkle value falling within arange from 6 to 10. Note that, the sparkle value is defined based on avalue of a standard deviation of luminance distribution of the display16 a under a condition in which the anti-glare film 1 is attached on thesurface of the display 16 a. The sparkle value can be obtained throughuse of a sparkle measurement apparatus 10 described later.

Further, the anti-glare layer 3 is set, and thus transmission imageclarity (image clarity) having an optical comb width of 0.5 mm has avalue falling within a range of 60% or less. The transmission imageclarity is a scale for quantitating unsharpness and distortion of lighttransmitted through the anti-glare layer 3, and is a measured valueobtained by a measurement method in accordance with JIS K7105.

Further, the anti-glare layer 3 is set to have a haze value fallingwithin a range of 50% or less. The haze value in the present embodimentis a measured value obtained by a measurement method in accordance withJIS K7136.

Further, the anti-glare layer 3 is set, and thus specular gloss(60-degree gloss) measured with 60-degree specular gloss has a valuefalling within 30% or less. The specular gloss is generally referred toas gloss indicating a value of a degree of specularly reflected light onan object surface, and is a measured value obtained by a measurementmethod in accordance with JIS K7136.

As described above, the anti-glare film 1 according to the presentembodiment can be designed through use of the sparkle value being anobjective quantitative evaluation for sparkle, and thus the sparklevalue falls within a range from 6 to 10. Thus, for example, as comparedto a case where design is provided based on a value indicating a sparkledegree by a subjective evaluation, sparkle can be stably suppressedwithin a desired ranged.

Further, the value of the transmissive clarity can be suppressed withina range of 60% or less while suppressing the haze value to fall within arange of 50% or less. Thus, high anti-glare property can be achievedwhile suppressing unsharpness of a character.

Further, the specular gloss (60-degree gloss) measured with 60-degreespecular gloss is set to a value falling within a range of 30% or less,which is a small value, and hence the anti-glare layer 3 can suppressreflection of external light on the surface of the display 16 a.

The adhesive layer 4 is arranged between the surface of the display 16 aand the substrate film 2, and fixes the anti-glare film 1 to the surfaceof the display 16 a.

Now, specific examples of the substrate film 2 and the anti-glare layer3 are described. Note that, description is given with an anti-glarelayer 3 formed by the phase separation method as the anti-glare layer 3in a first embodiment, an anti-glare layer 3 formed by the fine particledispersion method as the anti-glare layer 3 in a second embodiment, andan anti-glare layer 3 formed by the transfer molding method as theanti-glare layer 3 in a third embodiment.

Substrate Film

As a material of the substrate film 2, for example, glass, ceramics, anda resin can be exemplified. As the resin, a resin similar to a materialof the anti-glare layer 3 can be used. Examples of the preferablematerial of the substrate film 2 include a transparent polymer such as acellulose derivative (cellulose acetate such as cellulose triacetate(TAC) and cellulose diacetate, and the like), a polyester resin(polyethylene terephthalate (PET), polyethylene naphthalate (PEN),polybutylene terephthalate (PBT), polyarylate resin, and the like), apolysulfone resin (polysulfone, polyethersulfone (PES), and the like), apolyetherketone resin (polyetherketone (PEK), polyetheretherketone(PEEK), and the like), a polycarbonate resin (PC), a polyolefin resin(polyethylene, polypropylene, and the like), a cyclic polyolefin resin(a film “ARTON” (trade name) available from JSR Corporation, a film“ZEONEX” (trade name) available from Zeon Corporation, and the like), ahalogen-containing resin (polyvinylidene chloride, and the like), a(meth)acrylate-based resin, a styrene-based resin (polystyrene, and thelike), and a vinyl acetate or vinyl alcohol resin (polyvinyl alcohol,and the like).

The substrate film 2 may be stretched uniaxially or biaxially, butpreferably is optically isotropic and has a low index of refraction. Asthe optically isotropic substrate film 2, an unstretched film can beexemplified.

A thickness dimension of the substrate film 2 can be set as appropriate,and preferably is a value falling within a range of, for example, from 5μm to 2000 μm, more preferably a value falling within a range from 15 μmto 1000 μm, even more preferably a value falling within a range from 20μm to 500 μm.

First Embodiment

Configuration of Anti-Glare Layer According to First Embodiment

The anti-glare layer 3 in the first embodiment has a phase separationstructure with a plurality of resin components. As one example, theanti-glare layer 3 in the first embodiment has a structure in which aplurality of long and slender protruding (string-like shape or threadyshape) parts are formed on the surface due to a phase separationstructure with a plurality of resin components. The long and slenderprotruding parts are branched, and form a co-continuous phase structurein a dense state.

The anti-glare layer 3 in the first embodiment exerts anti-glareproperty with the plurality of long and slender protruding parts andrecessed parts positioned between the adjacent long and slenderprotruding parts. The anti-glare film 1 includes the anti-glare layer 3described above, and hence is excellent in balance of the haze value andthe transmission image clarity. The long and slender protruding partsare formed substantially in a mesh-like shape. Consequently, the surfaceof the anti-glare layer 3 in the first embodiment has a mesh-likestructure, in other words, a plurality of continuous or partly-missingirregular loop structures.

The structure described above is formed on the anti-glare layer 3 in thefirst embodiment, and thus formation of a lens shaped (sea-islandshaped) convex part on the anti-glare layer 3 can be prevented. Thus,light transmitted from the display 16 a through the anti-glare layer 3in the first embodiment is prevented from being refracted on therecesses and protrusions on the surface of the anti-glare layer 3, andthe pixels of the display 16 a are prevented from being magnified andvisually recognized due to a lens effect of the recesses and protrusionson the surface of the anti-glare layer 3. As a result, sparkle on thedisplay 16 a can be suppressed. Consequently, even when the anti-glarefilm 1 is attached on the display 16 a with high resolution pixels,sparkle can be suppressed at a high degree while securing anti-glareproperty, and unsharpness of a character and the like can also besuppressed.

Note that, the plurality of long and slender protruding parts may beindependent from or continuous to each other. As described later, thephase separation structure of the anti-glare layer 3 in the firstembodiment is formed by spinodal decomposition from a liquid phase (wetspinodal decomposition) through use of a solution being a raw materialof the anti-glare layer 3. With regard to details of the anti-glarelayer 3 in the first embodiment, for example, description of PatentDocument 4 can be referred.

Material of Anti-Glare Layer in First Embodiment

The plurality of resin components included in the anti-glare layer 3 inthe first embodiment are only required to be phase-separable. From aviewpoint of obtaining the anti-glare layer 3 having the long andslender protruding parts and achieving high scratch resistance, theplurality of resin components included in the anti-glare layer 3preferably include a polymer and a curable resin.

As a polymer included in the anti-glare layer 3 in the first embodiment,for example, a thermoplastic resin is exemplified. Examples of thethermoplastic resin include a styrene resin, a (meth)acrylic polymer, anorganic acid vinyl ester polymer, a vinyl ether polymer, ahalogen-containing resin, an olefin resin (including an alicyclic olefinresin), a polycarbonate resin, a polyester resin, a polyamide resin, athermoplastic polyurethane resin, a polysulfone resin (polyethersulfone,polysulfone, and the like), a polyphenylene ether resin (polymer of2,6-xylenol), a cellulose derivative (cellulose esters, cellulosecarbamates, cellulose ethers, and the like), a silicone resin(polydimethylsiloxane, polymethylphenylsiloxane, and the like), andrubber or elastomer (diene rubber such as polybutadiene andpolyisoprene, a styrene-butadiene copolymer, an acrylonitrile-butadienecopolymer, acrylic rubber, urethane rubber, silicone rubber, and thelike). These thermoplastic resins can be used alone or in combination oftwo or more.

A polymer having a functional group participating in a cure reaction ora functional group reacting with a curable compound may also beexemplified. The polymer may have a functional group at a principalchain or at a side chain.

Examples of the functional group include a condensible group, a reactivegroup (such as a hydroxyl group, an acid anhydride group, a carboxylgroup, an amino group or an imino group, an epoxy group, a glycidylgroup, and an isocyanate group), and a polymerizable group (a C₂₋₆alkenyl group such as vinyl, propenyl, isopropenyl, butenyl, and allyl,a C₂₋₆ alkynyl group such as ethynyl, propynyl, and butynyl, a C₂₋₆alkenylidene group such as vinylidene, and a group having apolymerizable group thereof (such as (meth)acryloyl group). Of thosefunctional groups, a polymerizable group is preferred.

Further, the anti-glare layer 3 in the first embodiment includes aplurality of kinds of polymers. Each of the polymers may bephase-separable from a liquid phase by spinodal decomposition, or may benon-miscible to each other. A combination of a first polymer and asecond polymer included in the plurality of kinds of polymers is notparticularly limited, and the polymers that are non-miscible to eachother at a temperature around a process temperature may be used.

For example, when the first polymer is a styrene resin (polystyrene, astyrene-acrylonitrile copolymer, and the like), the second polymer maybe a cellulose derivative (cellulose esters such as cellulose acetatepropionate), a (meth)acrylic resin (polymethyl methacrylate and thelike), an alicyclic olefin resin (a polymer having norbornene as amonomer, and the like), a polycarbonate resin, a polyester resin (polyC₂₋₄alkylene arylate copolyester and the like, and the like), and thelike.

Further, when the first polymer is a cellulose derivative (celluloseesters such as cellulose acetate propionate), the second polymer may bea styrene resin (polystyrene, a styrene-acrylonitrile copolymer, and thelike), a (meth)acrylic resin, an alicyclic olefin resin (a polymerhaving norbornene as a monomer, and the like), a polycarbonate resin, apolyester resin (poly C₂₋₄ alkylene arylate copolyester and the like),and the like.

The plurality of kinds of polymers may include at least cellulose esters(cellulose C₂₋₄ alkylcarboxylates such as cellulose diacetate, cellulosetriacetate, cellulose acetate propionate, and cellulose acetatebutyrate).

Here, a precursor of the curable resin included in the plurality ofresin components is cured by active energy rays (such as ultravioletrays and electron beams) at the time of manufacturing the anti-glarelayer 3, and thus the phase separation structure of the anti-glare layer3 in the first embodiment is fixed. Further, with thee curable resin asdescribed above, the anti-glare layer 3 in the first embodiment isprovided with scratch resistance and durability.

From a perspective of achieving scratch resistance, at least one polymerincluded in the plurality of kinds of polymers is preferably a polymerhaving a functional group, which is reactable with a curable resinprecursor, at a side chain. As the polymer forming the phase separationstructure, a thermoplastic resin or other polymers may be included inaddition to the two non-miscible polymers described above. A mass ratioM1/M2 of mass M1 of the first polymer to a mass M2 of the second polymerand a glass transfer temperature of the polymers can be set asappropriate.

As the curable resin precursor, for example, there can be exemplified acurable compound having a functional group that undergoes a reaction byactive energy rays (such as ultraviolet rays and electron beams), heat,and the like and forming a resin (particularly, a cured resin or acrosslinked resin) by curing or crosslinking by the functional group.

Examples of the compound described above include a thermosettingcompound or a thermosetting resin (a low molecular weight compoundhaving an epoxy group, a polymerizable group, an isocyanate group, analkoxysilyl group, a silanol group, and the like (for example, an epoxyresin, an unsaturated polyester resin, a urethane resin, and a siliconeresin)), and a photocurable (ionizing radiation-curable) compound thatis cured by ultraviolet rays, electron beams, or the like (anultraviolet light curable compound such as photocurable monomer andoligomer).

As the preferable curable resin precursor, there can be exemplified aphotocurable compound that is cured by ultraviolet rays, electron beams,or the like in a short period of time. Of those, the ultraviolet lightcurable compound is particularly practical. The photocurable compoundpreferably includes 2 or more (preferably about from 2 to 15 and morepreferably about from 4 to 10) polymerizable unsaturated bonds in themolecule. Consequently, resistance such as scratch resistance can beimproved. Specifically, the photocurable compound preferably is epoxy(meth)acrylate, urethane (meth)acrylate, polyester (meth)acrylate,silicone (meth)acrylate, and a polyfunctional monomer having at leasttwo polymerizable unsaturated bonds.

The curable resin precursor may include a curing agent in accordancewith a type thereof. For example, the thermosetting resin precursor mayinclude a curing agent such as amines and polyhydric carboxylic acids,and the photocurable resin precursor may include a photopolymerizationinitiator. Examples of the photopolymerization initiator include theknown components such as acetophenones or propiophenones, benzyls,benzoins, benzophenones, thioxanthones, and acylphosphine oxides.

Further, the curable resin precursor may include a curing accelerator.For example, the photocurable resin precursor may include a photocuringaccelerator (for example, tertiary amines (such as dialkylaminobenzoicacid ester), and a phosphine photopolymerization accelerator.

When manufacturing the anti-glare layer 3 in the first embodiment, atleast two components in the polymers included in the solution being theraw material of the anti-glare layer 3 and the curable resin precursorare used as a combination, which are phase-separated from each other ata temperature around a process temperature. Examples of the combinationfor phase separation include (a) a combination in which a plurality ofkinds of non-miscible polymers are phase-separated from each other, (b)a combination in which a polymer and a curable resin precursor that arenon-miscible are phase-separated from each other, (c) a combination inwhich a plurality of non-miscible curable resin precursors arephase-separated from each other. Of those combinations, in general, (a)a combination of a plurality of kinds of polymers, (b) a combination ofa polymer and a curable resin precursor are generally conceived, andparticularly, (a) a combination of a plurality of kinds of polymers ispreferable.

Here, in general, the polymers and a cured resin generated by curing ofthe curable resin precursor or a crosslinked resin have refractiveindexes different from each other. Further, in general, the plurality ofkinds of polymers (the first polymer and the second polymer) haverefractive indexes different from each other. A difference of therefractive indexes of the polymers and the cured resin or thecrosslinked resin, and a difference of the refractive indexes of theplurality kinds of polymers (the first polymer and the second polymer)are preferably values falling within a range from 0 to 0.2, and morepreferably values falling within a range from 0 to 0.07.

Further, the anti-glare layer 3 may include a plurality of fineparticles (filler) dispersed in a matrix resin. The fine particle may beany of an organic fine particle or an inorganic fine particle, and theplurality of fine particles may include a plurality of kinds of fineparticles.

As the organic fine particle, a crosslinked acrylic particle and acrosslinked styrene particle can be exemplified. Further, as theinorganic fine particle, a silica particle and an alumina particle canbe exemplified. Further, as one example, a difference in refractiveindexes of the fine particles and the matrix resin included in theanti-glare layer 3 may be set to a value falling within a range from 0to 0.2. The difference in refractive indexes is further desirably avalue falling within a range from 0 to 0.15, and more desirably a valuefalling within a range from 0 to 0.07.

An average particle diameter of the fine particles is not particularlylimited, and can be set to a value falling a range of, for example, from0.5 μm to 5.0 μm. The average particle diameter is further desirably avalue falling within a range from 0.5 μm to 4.0 μm, and more desirably avalue falling within a range from 1.0 μm to 3.0 μm.

Note that, the average particle diameter described herein is a50%-volume average particle diameter in a coulter counter method (thesame holds true in the average particle diameter mentioned below). Thefine particle may be solid or hollow. When the average particle diameterof the fine particles is excessively small, anti-glare property is lesslikely to be obtained, and when the average particle diameter of thefine particles is excessively large, sparkle on a display isdisadvantageously increased, which should be noted.

The thickness dimension of the anti-glare layer 3 in the firstembodiment can be set as appropriate, and is desirably a value fallingwithin a range, for example, from 0.3 μm to 20 μm, more desirably avalue falling within a range from 1 μm to 15 μm, and more desirably avalue falling within a range from 1 μm to 10 μm. In general, thethickness dimension can be set to a value falling within a range from 2μm to 10 μm (particularly, a value falling within a range from 3 μm to 7μm).

Note that, the anti-glare film 1 from which the substrate film 2 isomitted may be configured. In this case, the thickness dimension of theanti-glare layer 3 is desirably a value falling within a range from 1 μmto 100 μm, and more desirably a value falling within a range from 3 μmto 50 μm.

The anti-glare layer 3 in the first embodiment may include a knownadditive such as organic or inorganic particles, a stabilizer(antioxidant, an ultraviolet absorbing agent, and the like), asurfactant, a water soluble polymer, a filler, a crosslinker, a couplingagent, a coloring agent, a flame retardant, a lubricant, wax, anantiseptic, a viscosity adjusting agent, a thickening agent, a levelingagent, and an anti-foaming agent, as long as an optical property is notimpaired.

As one example, a method of manufacturing the anti-glare film 1according to the first embodiment includes preparing a solution being araw material of the anti-glare layer 3 in the first embodiment(hereinafter, also referred to simply as the “solution”), forming aphase separation structure by spinodal decomposition from a liquid phasewhile coating a surface of a prescribed support body (the substrate film2 in the first embodiment) with the solution prepared in preparing andevaporating a solvent in the solution, and curing a curable resinprecursor after forming.

Preparing

During preparing, the solution including the solvent and a resincomposition forming the anti-glare layer 3 in the first embodiment isprepared. The solvent may be selected in accordance with kinds andsolubility of the polymers included in the anti-glare layer 3 describedabove and the curable resin precursor. The solvent is only required todissolve uniformly at least solid contents (the plurality of kinds ofpolymers, the curable resin precursor, a reaction initiator, and anadditive thereto).

Examples of the solvent include ketones (acetone, methyl ethyl ketone,methyl isobutyl ketone, cyclohexanone, and the like), ethers (dioxane,tetrahydrofuran, and the like), aliphatic hydrocarbons (hexane and thelike), alicyclic hydrocarbons (cyclohexane and the like), aromatichydrocarbons (toluene, xylene, and the like), halogenated carbons(dichloromethane, dichloroethane, and the like), esters (methyl acetate,ethyl acetate, butyl acetate, and the like), water, alcohols (ethanol,isopropanol, butanol, cyclohexanol, and the like), cellosolves (methylcellosolve, ethyl cellosolve, and the like), cellosolve acetates,sulfoxides (dimethyl sulfoxide and the like), amides (dimethylformamide,dimethylacetamide, and the like). In addition, the solvent may be amixed solvent.

As the resin composition, a thermoplastic resin, a photocurablecompound, a photopolymerization initiator, and a composition including athermoplastic resin and a photocurable compound are desired.Alternatively, as the resin composition, a composition including theplurality of kinds of non-miscible polymers, a photocurable compound,and the photopolymerization initiator is desired.

A concentration of solutes (the polymers, the curable resin precursor,the reaction initiator, and the other additive) in the liquid mixturecan be adjusted as long as the phase separation of the plurality ofresin components is caused and a flow-casting property, a coatingproperty, and the like are not impaired.

Forming

During forming, the solution prepared in preparing is flow-casted on orcoats the surface of the support body (here, as one example, thesubstrate film 2). Examples of the flow-casting method or the coatingmethod of the solution include the known method such as a spray, aspinner, a roll coater, an air knife coater, a blade coater, a rodcoater, a reverse coater, a bar coater, a comma coater, a dip, a dipsqueeze coater, a die coater, a gravure coater, a micro gravure coater,and a silk screen coater.

The solvent is evaporated and removed through drying from the solutionwhich is flow-casted on or coats the surface of the support body. Alongwith condensation of the solution during evaporation, the phaseseparation of the plurality of resin components by spinodaldecomposition from a liquid phase is caused, and a phase separationstructure with a relatively regular inter-phase distance (a pitch or amesh diameter) is formed. A co-continuous phase structure of the longand slender protruding parts can be formed by setting a drying conditionand formulation that increase melt flowability of the resin componentsafter evaporation of the solvent to some extent.

Evaporation of the solvent is preferably performed by heating and dryingbecause the long and slender protruding parts are easily formed on thesurface of the anti-glare layer 3 in the first embodiment. When a dryingtemperature is excessively low or a drying time period is excessivelyshort, a quantity of heat is insufficiently provided to the resincomponents. Thus, melt flowability of the resin components is degraded,and the long and slender protruding parts are hard to be formed, whichshould be noted.

In contrast, when the drying temperature is excessively high or thedrying time period is excessively long, the long and slender protrudingparts that have been formed flow and reduce in height in some cases,although the structure thereof is maintained. Thus, in addition toadjustment of a combination of the phase-separation materials, thesparkle value, the specular gloss, the transmission image clarity, andthe haze value of the anti-glare layer 3, which are set to valuesfalling within ranges that satisfy the above-mentioned conditions, canbe achieved by adjusting the drying temperature and the drying timeperiod, and adjusting the height of the long and slender protrudingparts or the like. Further, during forming, by increasing an evaporationtemperature of the solvent or using components having a low viscosity asthe resin components, a co-continuous phase structure in which phaseseparation structures are connected can be provided.

As the phase separation of the plurality of resin components by spinodaldecomposition from a liquid phase advances, a co-continuous phasestructure is formed and coarsened. Consequently, the continuous phasebecomes a non-continuous phase, and a liquid droplet phase structure (anisolated-phase sea-island structure in a ball-like shape, a sphericalshape, a disk-like shape, an oval shape, or the like) is formed. Here,depending on an extent of the phase separation, an intermediatestructure between a co-continuous phase structure and a liquid dropletstructure (a phase structure in a process of shifting the co-continuousphase to the liquid droplet phase) can also be formed. After the solventis removed, a layer with a surface having fine recesses and protrusionsis formed.

Curing

During curing, the curable resin precursor included in the solution iscured, and hence the phase separation structure formed in forming isfixed. As a result, the anti-glare layer 3 in the first embodiment isformed. Curing of the curable resin precursor can be performed byheating, irradiation with active energy rays, or a combination of thesemethods in accordance with a kind of the curable resin precursor. Theactive energy rays for irradiation are selected in accordance with akind of a photocuring component or the like.

As needed, the irradiation of the active energy rays may be performed inan inert gas atmosphere. When the active energy rays are ultravioletrays, a far ultraviolet light lamp, a low-pressure mercury lamp, ahigh-pressure mercury lamp, an ultrahigh-pressure mercury lamp, ahalogen lamp, a laser light source (a helium-cadmium laser, an excimerlaser, and the like), and the like may be used as the light source.

Note that, when the adhesive layer 4 is formed, a solution including anadhesive component is adjusted, and then the solution coats the othersurface of the substrate film 2 and is dried by the known method such asthe flow-casting method or the coating method described above informing. With this, formation can be completed.

With the procedures as described above, the anti-glare film 1 accordingto the first embodiment is manufactured. Note that, when a peelablesupport body is used as the support body, the anti-glare film 1 formedof only the anti-glare layer 3 can be obtained by peeling the anti-glarelayer 3 from the support body. Further, when a non-peelable support body(preferably, a transparent support body such as the substrate film 2) isused as the support body, the anti-glare film 1 having a layeredstructure including the support body (the substrate film 2) and theanti-glare layer 3 can be obtained.

Here, as a method of suppressing sparkle of the display 16 a, forexample, it is conceivable to reduce the recesses and protrusions on thesurface of the anti-glare layer 3. However, there may be a possibilityof degradation of anti-glare property of the anti-glare film 1. However,in addition to reduction of the recesses and protrusions on theanti-glare layer 3, the inclination of the recesses and protrusions onthe anti-glare layer 3 is increased to make the recesses and protrusionssteep, and the number of recesses and protrusions is increased.Consequently, anti-glare property can be improved while suppressingsparkle on the display.

The recesses and protrusions described above can be formed on theanti-glare layer 3 by the above-mentioned spinodal decomposition in thefirst embodiment. However, with other methods, the recesses andprotrusions described above can also be formed on the anti-glare layer3. For example, in a case where a plurality of fine particles are usedfor forming recesses and protrusions on the surface of the anti-glarelayer 3 as in the second embodiment, materials are selected, and thus arepulsive interaction between the fine particles, and a resin or asolvent other than the fine particles is strong at the time of formingthe anti-glare layer 3. Consequently, suitable aggregation of the fineparticles is caused, and a distribution structure of steep recesses andprotrusions with high number density can be formed on the anti-glarelayer 3. Thus, in the following, the anti-glare layers 3 in the otherembodiments are described by mainly focusing on differences from thefirst embodiment.

Now, the anti-glare layers 3 in the other embodiments (the secondembodiment and the third embodiment) are described.

Second Embodiment

The anti-glare layer 3 in the second embodiment includes a matrix resinand a plurality of fine particles dispersed in the matrix resin. Theplurality of fine particles are formed in a spherical shape. However,the plurality of particles are not limited thereto, and may be formed ina substantially ball-like shape or an oval shape. Further, the fineparticle is formed to be solid, but may be formed to be hollow. When thefine particle is formed to be hollow, in a hollow part of the fineparticle may be filled with air or other gases. In the anti-glare layer3 in the second embodiment, the fine particles may be dispersed asprimary particles, or a plurality of secondary particles formed byaggregation of a plurality of fine particles may be dispersed.

A difference in refractive indexes of the matrix resin and the fineparticles is set to a value falling within a range from 0 to 0.2. Thedifference in refractive indexes is further desirably a value fallingwithin a range from 0 to 0.15, and more desirably a value falling withina range from 0 to 0.07.

The fine particles have an average particle diameter set to a valuefalling within a range of from 0.5 μm to 5.0 μm. The average particlediameter of the fine particles is further desirably a value fallingwithin a range from 0.5 μm to 4.0 μm, and more preferably a valuefalling within a range from 1.0 μm to 3.0 μm.

Further, variation in particle diameter of the fine particles ispreferably small. For example, in particle diameter distribution of thefine particles included in the anti-glare layer 3, an average particlediameter of 50 wt. % or greater of the fine particles included in theanti-glare layer 3 preferably has variation within 1.0 μm.

As described above, uniform and suitable recesses and protrusions areformed on the surface of the anti-glare layer 3 due to the fineparticles having a relatively uniform particle diameter and the averageparticle diameter set to fall within the above-mentioned range. Withthis, sparkle on the display 16 a can be suppressed while securinganti-glare property.

Further, the weight of the matrix resin and the total weight of theplurality of fine particles in the anti-glare layer 3 can be set asappropriate. In the second embodiment, a ratio G2/G1 of a weight G1 ofthe matrix resin of the anti-glare layer 3 to a total weight G2 of theplurality of fine particles included in the anti-glare layer 3 is set toa value falling within a range from 0.02 to 0.15. The ratio G2/G1 ispreferably a value falling within a range from 0.04 to 0.15, and morepreferably a value falling within a range from 0.04 to 0.12.

The fine particles dispersed in the matrix resin may be inorganic ororganic, and preferably have satisfactory transparency. As the organicfine particles, plastic beads can be exemplified. Examples of theplastic beads include styrene beads (a refractive index of 1.59),melamine beads (a refractive index of 1.57), acrylic beads (a refractiveindex of 1.49), acryl-styrene beads (a refractive index of 1.54),polycarbonate beads, polyethylene beads, and the like. The plastic beadsdesirably have hydrophobic groups on surfaces thereof. As the plasticbeads, styrene beads can be exemplified.

As the matrix resin, at least any of a photocurable resin cured byactive energy rays, a solvent drying-type resin cured by drying thesolvent added during coating, or the thermosetting resin can beexemplified.

Examples of the photocurable resin include a resin having a acrylatefunctional group such as a polyester resin with a relatively lowmolecular weight, a polyether resin, an acrylic resin, an epoxy resin,an urethane resin, an alkyd resin, a spiroacetal resin, a polybutadieneresin, a polythiol polyene resin, an oligomer such as a (meth)acrylatewhich is a polyfunctional compound such as polyhydric alcohol, aprepolymer, and a reactive diluent.

Specific examples of those include a monofunctional monomer and apolyfunctional monomer of, for example, ethyl (meth)acrylate, ethylhexyl(meth)acrylate, styrene, methyl styrene, N-vinyl pyrrolidone, such aspolymethylolpropane tri(meth)acrylate, hexanediol (meth)acrylate,tripropylene glycol di(meth)acrylate, diethylene glycoldi(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritolhexa(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and neopentylglycol di(meth)acrylate.

When the photocurable resin is an ultraviolet light curable resin, it ispreferred to use the photopolymerization initiator. Examples of thephotopolymerization initiator include acetophenones, benzophenones,Michler benzoyl benzoate, α-amyl oxime ester, tetramethylthiurammonosulfide, and thioxanthones. Further, the photocurable resin ispreferably used by mixing with a photosensitizer. As thephotosensitizer, n-butylamine, triethylamine, poly-n-butylphosphine, andthe like can be exemplified.

As the solvent drying-type resin, a publicly known thermoplastic resincan be exemplified. Examples of the thermoplastic resin include astyrene resin, a (meth)acrylate-based resin, a vinyl acetate-basedresin, a vinyl ether resin, a halogen-containing resin, an alicyclicolefin resin, a polycarbonate resin, a polyester resin, a polyamideresin, a cellulose derivative, a silicone resin, rubber or elastomer,and the like. As the solvent drying-type resin, a resin, which can besolved in an organic solvent, and is excellent particularly inmoldability, film-formability, transparency, and weather resistance, isdesired. Examples of the solvent drying-type resin as described aboveinclude a styrene resin, a (meth)acrylate-based resin, an alicyclicolefin resin, a polyester resin, and a cellulose derivative (celluloseesters and the like).

Here, when the material of the substrate film 2 is a cellulose resinsuch as cellulose triacetate (TAC), a cellulose resin can be exemplifiedas a thermoplastic resin used as the solvent drying-type resin. Examplesof the cellulose resin include a cellulose derivative such as cellulosenitrate, acetyl cellulose, acetyl butyl cellulose, ethyl cellulose,methyl cellulose, cellulose acetate propionate, and ethyl hydroxyethylcellulose. A cellulose resin is used as the solvent drying-type resin,and thus the substrate film 2 and the anti-glare layer 3 can be broughtinto close contact with each other satisfactorily. Also, excellenttransparency can be obtained in the anti-glare film 1.

Further, other than the above, examples of the solvent drying-type resininclude a vinyl resin, an acetal resin, an acrylate-based resin, apolystyrene resin, a polyamide resin, and a polycarbonate resin.

Examples of the thermosetting resin include a phenol resin, a urearesin, a diallyl phthalate resin, a melamine resin, a guanamine resin,an unsaturated polyester resin, a polyurethane resin, an epoxy resin, anaminoalkyd resin, a melamine-urea co-condensated resin, a siliconeresin, and a polysiloxane resin When the thermosetting resin is used asthe matrix resin, at least any of a crosslinker, a curing agent such asa photopolymerization initiator, a photopolymerization accelerator, asolvent, and a viscosity adjusting agent or the like may be used incombination.

As one example, a method of manufacturing the anti-glare film 1according to the second embodiment includes preparing a solution being araw material of the anti-glare layer 3 in the second embodiment, coatinga surface of a prescribed support body (the substrate film 2 in thesecond embodiment) with the solution prepared in preparing, and curing aresin in the solution used for coating.

Preparing

During preparing, the solution including the solvent, and a resincomposition and fine particles for forming the anti-glare layer 3 in thesecond embodiment is prepared. As the solvent, at least any of alcohols(such as isopropyl alcohol, methanol, and ethanol), ketones (such asmethyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), andcyclohexanone), esters (such as methyl acetate, ethyl acetate, and butylacetate), halogenated hydrocarbon, or aromatic hydrocarbon (such astoluene and xylene) can be exemplified. A publicly known leveling agentmay further be added to solution. For example, by using a fluorine orsilicone leveling agent, satisfactory scratch resistance can be providedto the anti-glare layer.

Coating and Curing

During coating, the solution prepared in preparing is flow-casted on orcoats the surface of the support body (here, as one example, thesubstrate film 2) by a method similar to that in the first embodiment.The solvent is evaporated and removed through drying from the solutionwhich is flow-casted on or coats the surface of the support body.

When the matrix resin is a photocurable resin, as one example, curing byultraviolet light or electron beams is performed after coating. As theultraviolet light source, a light source such as various types ofmercury lamps, an ultraviolet ray carbon arc lamp, black light, and ametal halide lamp can be exemplified. Further, as a wavelength region ofthe ultraviolet light, for example, a wavelength region from 190 nm to380 nm can be exemplified.

Further, as an electron beam source, a publicly known electron beamaccelerator can be exemplified. Specifically, various electron beamaccelerators such as a Van de Graaff type, a Cockcroft-Walton type, aresonant transformer type, an insulating core transformer type, a lineartype, a dynamitron type, and a high-frequency type can be exemplified.

The matrix resin included in the solution is cured, and hence thepositions of the fine particles in the matrix resin are fixed.Consequently, the plurality of fine particles are dispersed in thematrix resin, and the anti-glare layer having a structure in which therecesses and protrusions are formed on the surface due to the fineparticles is formed.

In the anti-glare film 1 according to the second embodiment, adifference in refractive indexes of the matrix resin and the fineparticles is set to fall within a predetermined range, and the pluralityof fine particles are dispersed in the matrix resin. Consequently,sparkle on the display 16 a can be suppressed while securingsatisfactory anti-glare property.

Third Embodiment

The anti-glare layer 3 of the anti-glare film 1 according to the thirdembodiment has a structure in which recesses and protrusions are shapedon a surface on a side opposite to the substrate film 2 side. Theanti-glare layer 3 in the third embodiment is formed of a resin layer.The resin layer is formed of the same material as that of the matrixresin included in the anti-glare layer 3 in the second embodiment, asone example.

As one example, the anti-glare film 1 according to the third embodimentis manufactured by forming a coat layer formed of a curable resin on thesubstrate film 2, shaping a surface of the coat layer into recesses andprotrusions, and curing the coat layer. FIG. 2 is a view illustrating amethod of manufacturing the anti-glare film 1 according to the thirdembodiment. In the example of FIG. 2 , an ultraviolet light curableresin is used as a curable resin.

As illustrated in FIG. 2 , in this manufacturing method, the substratefilm 2 is unwound from an unwind roll (not shown), and is conveyed in apredetermined direction. A downstream end of the substrate film 2 in aconveyance direction is inserted to a nip point N1 of a pair of rolls 21and 22.

An ultraviolet light curable resin precursor adheres to acircumferential surface of the roll 22 from a circumferential surface ofa roll 23 that is adjacent to and axially supported by the roll 22. Thesubstrate film 2 passes through the nip point N1, the ultraviolet lightcurable resin precursor coats one surface of the substrate film 2.

A layer of the ultraviolet light curable resin precursor coating thesubstrate film 2 (hereinafter, referred to as a coat layer) is pressedtogether with the substrate film 2 at a nip point of rolls 21 and 24.The roll 24 is a roll-shaped die (an embossing roll) with fine recessesand protrusions formed on a circumferential surface thereof, andtransfers the recesses and protrusions onto a surface of the coat layerwhen passing though the nip point N2 of the rolls 21 and 24.

The coat layer onto which the recesses and protrusions are transferredfrom the roll 24 is cured by ultraviolet light emitted from aultraviolet light lamp 26 provided below the rolls 21 and 24.Consequently, the anti-glare layer 3 of the anti-glare film 1 accordingto the third embodiment is formed. The anti-glare film 1 according tothe third embodiment thus manufactured is released from the roll 24 andconveyed in a predetermined direction by a roll 25 that is adjacent toand axially supported by the roll 24.

Here, the recesses and protrusions on the surface of the roll 24 areformed through blasting by causing blast particles having apredetermined particle diameter to strike, and a shape of the recessesand protrusions formed on the coat layer of the anti-glare film 1 can beadjusted by adjusting a blast particle diameter.

As the substrate film 2 of the anti-glare film 1 according to the thirdembodiment, a polyethylene terephthalate (PET) film, a cellulosetriacetate (TAC) film, a cyclo olefin polymer (COP) film, an acrylicresin film, or a polycarbonate resin film can suitably be used.

As described above, the method of manufacturing the anti-glare film 1according to the third embodiment includes (a) coating the substratefilm 2 with the curable resin precursor, (b) manufacturing theroll-shaped die having recesses and protrusions on the surface thereofby causing the blast particles to strike, (c) transferring the recessesand protrusions onto the surface of the curable resin precursor thatcoats the substrate film 2, through use of the roll-shaped die, and (d)forming the anti-glare layer 3 having the surface with the recesses andprotrusions formed thereon by curing the curable resin precursor ontowhich the recesses and protrusions are transferred.

The average particle diameter of the blast particles used in (b) can beset as appropriate, and can be set to a value falling within a range offrom 10 μm to 50 μm, as one example. The average particle diameter ofthe blast particles is further desirably a value falling within a rangefrom 20 μm to 45 μm, and more desirably a value falling within a rangefrom 30 μm to 40 μm. Consequently, the anti-glare layer 3 in the thirdembodiment having a surface with the recesses and protrusions shapedthereon can be obtained.

Note that, the die used in the third embodiment may be other than theroll-shaped die, and may be a plate-shaped die (an embossing plate), forexample. Further, a coat layer (a resin layer) is formed on one surfaceof the substrate film 2 in the third embodiment, and then the surface ofthe coat layer is shaped by the die. In this manner, the anti-glarelayer 3 in the third embodiment may be formed. Further, in the exampledescribed above, the coat layer is cured after the surface of the coatlayer is shaped. However, shaping and curing of the coat layer may beperformed in parallel.

As one example of a material of the die, metal, plastic, and wood can beexemplified. A coating film may be provided on a contact surface of thedie with the coat layer, and thus durability (wear resistance) of thedie is improved. As one example of a material of the blast particles,metal, silica, alumina, and glass can be exemplified. The blastparticles can be caused to strike against the surface of the die by, forexample, a pressure force of air or liquid. Further, when the curableresin precursor is an electron beam curable type, an electron beamsource such as an electron beam accelerator can be used in place of theultraviolet light lamp 26. When the curable resin precursor is athermosetting type, a heat source such as a heater can be used in placeof the ultraviolet light lamp 26.

Note that, the anti-glare layer 3 of the anti-glare film 1 according toeach of the embodiments described above may further include an upperlayer arranged on the surface on the side opposite to the substrate film2 side. By providing the upper layer, an external haze of the anti-glarelayer 3 can be adjusted easily. Moreover, the anti-glare film 1 can beprotected easily from outside.

A thickness of the upper layer can be set as appropriate, and can be setto a value falling within a range, for example, from 10 nm to 2.0 μm.The thickness of the upper layer is further desirably a value fallingwithin a range from 50 nm to 1.0 μm, and more desirably a value fallingwithin a range of from 70 nm to 0.5 μm.

Next, an evaluation device and an evaluation method for quantitativelyevaluating sparkle on the anti-glare film 1 according to each of theembodiments described above are described with reference to FIG. 3 .

Sparkle Measurement Apparatus

FIG. 3 is a view illustrating one example of a schematic configurationof the sparkle measurement apparatus 10 according to an embodiment ofthe present invention. The sparkle measurement apparatus 10 is anapparatus that inspects an extent of sparkle on the display 16 a of thedisplay device 16 on which the anti-glare film 1 is attached. Thesparkle measurement apparatus 10 includes an enclosure 11, an imagingdevice 12, a holding portion (adjusting portion) 13, an imaging devicestand 14, a display device stand (adjusting portion) 15, and an imageprocessing device 17.

The enclosure 11 is for providing a dark space being a measurement spacefor performing sparkle evaluation, and has a hollow rectangularparallelepiped shape. The imaging device 12, the holding portion 13, theimaging device stand 14, the image display stand 15, and the displaydevice 16 being subjected to sparkle evaluation are housed in theenclosure 11. Note that, the enclosure 11 has a configuration thatprevents light from entering the enclosure 11 from outside at the timeof imaging performed by the imaging device 12.

As one example, the imaging device 12 is an area camera including a lens18 and an imaging element, and captures an image of an image displayedon the display 16 a. The imaging device 12 is held by the holdingportion 13, and thus the lens 18 and the display 16 a face with eachother. The imaging device 12 is connected to the image processing device17, and image data captured by the imaging device 12 is transmitted tothe image processing device 17.

The holding portion 13 is a member in a bar-like shape extending in avertical direction (in an up-and-down direction in FIG. 3 ). The baseend of the holding portion 13 is fixed by the imaging device stand 14,and the distal end thereof holds the imaging device 12. Further, theimaging device 12 is movable in the vertical direction by the holdingportion 13, and a relative distance between the display 16 a and thelens 18 can be changed.

The display device 16 is placed on the upper surface of the imagedisplay stand 15 under a state in which the display 16 a with theanti-glare film 1 attached thereon faces the imaging device 12. Theimage display stand 15 can support the display device 16, and thus thesurface of the display 16 a with the anti-glare film 1 attached thereonfaces the imaging device 12 and becomes a horizontal surface. The imagedisplay stand 15 can move the display device 16 in the verticaldirection, and thus a relative distance between the display 16 a and thelens 18 is changed.

In the sparkle measurement apparatus 10, by adjusting a relativedistance between the imaging device 12 and the display 16 a, a size ofan image displayed in the display 16 a, which is captured as an image bythe imaging element of the imaging device 12, is adjusted. In otherwords, a pixel size of the image displayed on the display 16 a, which iscaptured by the imaging element of the imaging device 12 per unit pixel(for example, one pixel), is adjusted.

The image processing device 17 executes data processing of the imagedata captured by the imaging device 12. Specifically, the imageprocessing device 17 obtains, from the image data captured by theimaging device 12, a value of a standard deviation of luminance of theimage displayed on the display 16 a.

the image processing device 17 in the present embodiment includes aninput unit to which the image data captured by the imaging device 12 isinput, an image processing unit that subjects the input image data toimage processing, an output unit that outputs a result obtained byprocessing of the image processing unit to a display instrument, aprinting device, or the like (not shown), and the like.

Note that, as the method of adjusting a pixel size of the imagedisplayed on the display 16 a, which is captured by the imaging elementper unit pixel (for example, one pixel), a method of varying a focallength of the imaging device 12 may be adopted when the lens 18 includedin the imaging device 12 is a zoom lens, in addition to the method ofvarying a relative distance between the imaging device 12 and thedisplay 16 a.

Sparkle Evaluation Method

Next, a sparkle evaluation method through use of the sparkle measurementapparatus 10 is described. In this sparkle evaluation method, forconvenience of the evaluation, display is performed on the display 16 ahaving a surface on which the anti-glare film 1 is attached while thesurface is caused to emit one-color light evenly (green as one example)in advance.

First, adjustment is performed, and thus a pixel size of the display 16a with the anti-glare film 1 attached thereon, which is captured by theimaging element of the imaging device 12 per unit pixel, is set to apredetermined value (adjusting).

At the time of adjusting, a relative distance between the imaging device12 and the display 16 a with the anti-glare film 1 attached thereon isadjusted in accordance with the number of effective pixels of theimaging element of the imaging device 12. Emission lines of the pixelsof the image displayed on the display 16 a with the anti-glare film 1attached thereon are adjusted to be invisible or visible to an extentthat does not affect sparkle evaluation in the image data captured bythe imaging device 12.

Note that, a relative distance between the imaging device 12 and thedisplay device 16 is desirably set in consideration of an actual usagemode of the display device 16 (for example, a relative distance betweeneyes of a user and the display 16 a).

After adjusting is performed, a measurement area for evaluating sparkleon the display 16 a with the anti-glare film 1 attached thereon is set(setting). At the time of setting, the measurement area can be set asappropriate in accordance with, for example, a size of the display 16 a.

After adjusting is performed, the measurement area of the display 16 awith the anti-glare film 1 attached thereon is captured as an image bythe imaging device 12 (imaging). In this case, as one example, at leastone of an exposure time of the imaging device 12 or luminance of all thepixels of the display 16 a is adjusted, and thus image data relating toa gray scale image with 8-bit gradation display and an average luminanceof 170 tones is obtained. At the time of imaging, the captured imagedata is input to the image processing device 17.

After imaging is performed, the image processing device 17 obtains, fromthe image data, a deviation of luminance of the image in the measurementarea of the display 16 a with the anti-glare film 1 attached thereon(calculating). At the time of calculating, a deviation of luminance canbe expressed in a numerical form by obtaining a standard deviation ofluminance distribution. Here, a sparkle degree of the display 16 a withthe anti-glare film 1 attached thereon is larger as a deviation ofluminance of the display 16 a with the anti-glare film 1 attachedthereon is larger. Based on this, it can be quantitatively andobjectively evaluated that a smaller value of a standard deviation ofluminance distribution indicates less sparkle. Further, at the time ofadjusting, the emission lines of the display 16 a with the anti-glarefilm 1 attached thereon are adjusted to an extent that does not affectsparkle evaluation. Thus, luminance unevenness due to the emission linesis suppressed, and accurate sparkle evaluation can be performed.

With the procedures as described above, a standard deviation ofluminance distribution of the display 16 a having a surface with theanti-glare film 1 attached thereon can be obtained, and sparkleevaluation can be performed based on a magnitude of the value.

EXAMPLES AND COMPARATIVE EXAMPLES

Hereinafter, the present invention is described in more detail based onExamples, but the present invention is not limited to these Examples.

Each of Examples 1 to 3 is one example of the anti-glare film 1 that wasmanufactured by the phase separation method and satisfied the conditionsof the sparkle value falling within a range of from 6 to 10, thespecular gloss (60-degree gloss) of 30% or less, the transmission imageclarity (image clarity) of 60% or less, which had an optical comb widthof 0.5 mm, and the haze value of 50% or less. In other words, each ofExamples 1 to 3 is one example of the anti-glare film 1 that was capableof satisfying the above-mentioned conditions with the recesses andprotrusions formed on the surface of the anti-glare film 1 by the phaseseparation method.

Example 4 is one example of the anti-glare film 1 that was manufacturedby the fine particle dispersion method and satisfied the conditions ofthe sparkle value falling within a range from 6 to 10, the speculargloss (60-degree gloss) of 30% or less, the transmission image clarity(image clarity) of 60% or less, which had an optical comb width of 0.5mm, and the haze value of 50% or less. In other words, a difference ofrefractive indexes of the matrix resin of the anti-glare layer 3 of theanti-glare film 1 and the plurality of fine particles dispersed in thematrix resin was adjusted to 0.07 or less, and thus Example 4 is oneexample of the anti-glare film 1 capable of satisfying theabove-mentioned conditions.

In contrast, each of Comparative Examples 1 to 3 is one example of theanti-glare film 1 manufactured by the fine particle dispersion method,and each of Comparative Examples 4 and 5 is one example of theanti-glare film 1 manufactured by the transfer forming method.

Raw Material

The raw materials used in Examples and Comparative Examples are asfollows. Note that, with respect to raw materials that are cured bycrosslinking, the refractive indexes thereof described below indicaterefractive indexes after crosslinking (after curing).

Acrylate-based polymer having a polymerizable group: “Cyclomer P”available from Daicel-Allnex Ltd., (a refractive index of 1.51).

Cellulose acetate propionate: “CAP-482-20” available from EastmanChemical Company, (a refractive index of 1.49), degree ofacetylation=2.5%, degree of propionylation=46%, number average molecularweight of 75000 in terms of polystyrene.

Nanosilica (a refractive index of 1.46)-containing acrylate-basedultraviolet light curable compound: “UVHC7800G” available from MomentivePerformance Materials Japan LLC., (a refractive index of 1.52).

Silicone acrylate: “EB1360” available from Daicel-Allnex Ltd., (arefractive index of 1.52).

Urethane acrylate: “UA-53H” available from Shin-Nakamura Chemical Co.,Ltd., (a refractive index of 1.52).

Dipentaerythritol hexaacrylate: “DPHA” available from Daicel-AllnexLtd., (a refractive index of 1.52).

Pentaerythritol tetraacrylate: “PETRA” available from Daicel-AllnexLtd., (a refractive index of 1.52).

Silica (a refractive index of 1.46)-containing acrylated-basedultraviolet light curable compound: “Z-757-4RL” available from AicaKogyo Company, Limited, (a refractive index of 1.52).

Fluorine compound having a polymerizable group: fluorine anti-foulingadditive “KY-1203” available from Shin-Etsu Chemical Co., Ltd.

Alkylfenon photopolymerization initiator (photopolymerization initiatorA): “IRGACURE 184” available from BASF SE.

Alkylfenon photopolymerization initiator (photopolymerization initiatorB): “IRGACURE 907” available from BASF SE.

Polyethylene terephthalate (PET) film: “Diafoil” available fromMitsubishi Plastics, Inc.

Cellulose triacetate (TAC) film: “FUJITACTG60UL” available from FUJIFILMCorporation.

Example 1

50 parts by mass of an acrylate-based polymer having a polymerizablegroup, 4 parts by mass of cellulose acetate propionate, 76 parts by massof urethane acrylate, 1 part by mass of silicone acrylate, 1 part bymass of the photopolymerization initiator A, and 1 part by mass of thephotopolymerization initiator B were dissolved in a solvent obtained bymixing 176 parts by mass of methyl ethyl ketone and 28 parts by mass of1-butanol, and thus a solution was prepared.

The solution was flow-casted on a PET film (the substrate film 2) usinga wire bar (#18), and then was left in an oven at 80° C. for 1 minute toevaporate a solvent and form a coat layer having a thickness ofapproximately 9 μm. Further, for example, ultraviolet light curingprocessing of the coat layer was performed by irradiating the coat layerwith ultraviolet light from an ultraviolet light lamp such as ahigh-pressure mercury lamp for approximately five seconds. In thismanner, the anti-glare layer 3 was formed, and thus an anti-glare filmof Example 1 was obtained.

Example 2

50 parts by mass of an acrylate-based polymer having a polymerizablegroup, 4 parts by mass of cellulose acetate propionate, 76 parts by massof urethane acrylate, 1 part by mass of silicone acrylate, 1 part bymass of a fluorine compound having a polymerizable group, 1 part by massof the photopolymerization initiator A, and 1 part by mass of thephotopolymerization initiator B were dissolved in a solvent obtained bymixing 176 parts by mass of methyl ethyl ketone and 28 parts by mass of1-butanol, and thus a solution was prepared.

The solution was flow-casted on a PET film (the substrate film 2) usinga wire bar (#14), and then was left in an oven at 80° C. for 1 minute toevaporate a solvent and form a coat layer having a thickness ofapproximately 6 μm. Further, ultraviolet light curing processing of thecoat layer was performed by irradiating the coat layer with ultravioletlight from an ultraviolet light lamp for approximately five seconds. Inthis manner, the anti-glare layer 3 was formed, and thus an anti-glarefilm of Example 2 was obtained.

Example 3

17.5 parts by mass of acrylate-based polymer having a polymerizablegroup, 3.0 parts by mass of cellulose acetate propionate, 149.7 parts bymass of a nanosilica-containing acrylate-based ultraviolet light curablecompound, 0.2 part by mass of silicone acrylate, 1 part by mass of thephotopolymerization initiator A, and 1 part by mass of thephotopolymerization initiator B were dissolved in a solvent obtained bymixing 129 parts by mass of methyl ethyl ketone, 24 parts by mass of1-butanol, and 13 parts by mass of 1-methoxy-2-propanol, and thus asolution was prepared.

The solution was flow-casted on a TAC film (the substrate film 2) usinga wire bar (#12), and then was left in an oven at 80° C. for 1 minute toevaporate a solvent and form a coat layer having a thickness ofapproximately 4 μm. Further, ultraviolet light curing processing wasperformed by irradiating the coat layer with ultraviolet light from anultraviolet light lamp for approximately five seconds. In this manner,the anti-glare layer 3 was formed, and thus an anti-glare film ofExample 3 was obtained.

Example 4

A solution was prepared by mixing 50 parts by mass of a silica (arefractive index of 1.46)-containing acrylate-based ultraviolet lightcurable compound (a refractive index of 1.52) and 50 parts by mass of1-butanol.

The solution was flow-casted on a PET film (the substrate film 2) usinga wire bar (#16), and then was left in an oven at 80° C. for 1 minute toevaporate a solvent and form a coat layer having a thickness ofapproximately 7 μm. Further, ultraviolet light curing processing wasperformed by irradiating the coat layer with ultraviolet light from anultraviolet light lamp for approximately five seconds. In this manner,the anti-glare layer 3 was formed, and thus an anti-glare film ofExample 4 was obtained. Note that, when G1 indicated the weight of thematrix resin (acrylate-based ultraviolet light curable compound) and G2indicated a weight of the fine particles (silica) included in theanti-glare layer 3, the ratio G2/G1 of those weights was 0.14.

Comparative Example 1

As the transparent base material, triacetyl cellulose (available fromFUJIFILM Corporation, a thickness of 80 μm) was prepared.

Pentaerythritol triacrylate (“PETA” available from Daicel-Allnex Ltd., arefractive index of 1.51) was used as a transparent resin. Then, withrespect to 100 parts by mass of the transparent resin, 10.0 parts bymass of styrene-acrylic copolymer particles (a refractive index of 1.51,an average particle diameter of 9.0 μm) and 16.5 parts by mass ofpolystyrene particles (a refractive index of 1.60, an average particlediameter of 3.5 μm) were included as transparent particles. Then, 190parts by mass of a mixed solvent of toluene (a boiling point at 110° C.)and cyclohexanone (a boiling point at 156° C.) in a mass ratio of 7:3are mixed with 100 parts by mass of the transparent resin. As a result,a resin composition was obtained.

The resin composition was applied on the transparent base, and was driedfor one minute while purging drying air at a flow speed of 1 m/s at 85°C. Note that, the coating thickness is 5 μm. After that, UV light curingprocessing was performed by irradiating a transparent resin withultraviolet light from an ultraviolet light lamp (200 mJ/cm² in anitrogen atmosphere). In this manner, the anti-glare layer 3 was formed,and thus an anti-glare film of Comparative Example 1 was obtained.

Comparative Example 2

As the transparent base material, triacetyl cellulose (available fromFUJIFILM Corporation, a thickness of 80 μm) was prepared.

A mixture of pentaerythritol triacrylate (“PETA” available fromDaicel-Allnex Ltd.), dipentaerythritol hexaacrylate (“DPHA” availablefrom Daicel-Allnex Ltd.), and polymethyl methacrylate (“BR85” availablefrom MITSUBISHI RAYON CO., LTD.) was used as a transparent resin (a massratio of PETA/DPHA/PMMA=86/5/9) (a refractive index of 1.51). Then, withrespect to 100 parts by mass of the transparent resin, 18.5 parts bymass of polystyrene particles (a refractive index of 1.60, an averageparticle diameter of 3.5 μm) and 3.5 parts by mass of styrene-acryliccopolymer particles (a refractive index of 1.56, and average particlediameter of 3.5 μm) were included as transparent particles. Then, 190parts by mass of a mixed solvent of toluene (a boiling point at 110° C.)and cyclohexanone (a boiling point at 156° C.) in a mass ratio of 7:3are mixed with 100 parts by mass of the transparent resin. As a result,a resin composition was obtained.

The resin composition was applied on the transparent base, and was driedfor one minute while purging drying air at a flow speed of 0.2 m/s at70° C. Note that, the coating thickness is 3.5 μm. After that, UV lightcuring processing was performed by irradiating a transparent resin withultraviolet light from an ultraviolet light lamp (200 mJ/cm² in anitrogen atmosphere). In this manner, the anti-glare layer 3 was formed,and thus an anti-glare film of Comparative Example 2 was obtained.

Comparative Example 3

As the transparent base material, triacetyl cellulose (available fromFUJIFILM Corporation, a thickness of 80 μm) was prepared.

Pentaerythritol triacrylate (“PE-3A” available from Kyoeisha ChemicalCo., Ltd., a refractive index of 1.53) was used as a transparent resin.Then, with respect to 100 parts by mass of the transparent resin, 26parts by mass of silica particles (“5550F” available from Tosoh SilicaCorporation, a refractive index of 1.47, an average particle diameter of1.1 μm) and 6.6 parts by mass of polystyrene particles (a refractiveindex of 1.59, an average particle diameter of 3.5 μm) were included astransparent particles. Then, 5.3 parts by mass of thephotopolymerization initiator A and 138 parts by mass of toluene (aboiling point at 110° C.) as a solvent are mixed with each other. As aresult, the resin composition was obtained.

The resin composition was applied on the transparent base, and was driedfor one minute while purging drying air at a flow speed of 0.2 m/s at90° C. Note that, the coating thickness is 5 μm. After that, UV curingprocessing was performed by irradiating a transparent resin withultraviolet light from an ultraviolet light lamp (200 mJ/cm² in anitrogen atmosphere). In this manner, the anti-glare layer 3 was formed,and thus an anti-glare film of Comparative Example 3 was obtained.

Comparative Examples 4 and 5

Each of the anti-glare films in Comparative Examples 4 and 5 wasmanufactured by forming, on a substrate film, a coat layer which wasformed of an ultraviolet light curable resin and had a surface withrecesses and protrusions transferred thereon through use of a die. Themanufacturing process of the anti-glare film with the transfer moldingmethod has already described above, and hence detailed descriptionthereof is omitted.

That is, the method of manufacturing the anti-glare film in ComparativeExamples 4 and 5 included (a) coating the substrate film with theultraviolet light curable resin precursor, (b) manufacturing theroll-shaped die having recesses and protrusions on the surface thereofby causing the blast particles to strike, (c) transferring the recessesand protrusions onto the surface of the ultraviolet light curable resinprecursor that coated the substrate film, through use of the roll-shapeddie, and (d) forming the coat layer having the surface with the recessesand protrusions formed thereon by curing, by irradiation withultraviolet light, the ultraviolet light curable resin precursor ontowhich the recesses and protrusions are transferred.

Here, in (b), a roll-shaped die was manufactured while varying a valueof a blast particle diameter to fall within a range of from 10 μm to 40μm, and two kinds of films (Comparative Examples 4 and 5) havingdifferent haze (Hz) values were manufactured by the above-mentionedmanufacturing methods.

Note that, a TAC (cellulose triacetate) film was suitably used as thesubstrate film. Further, each of the anti-glare films in Examples 1 to 4and Comparative Examples 1 to 5 was evaluated by measuring the followingitems.

Haze and Total Light Transmittance

Measurement was performed using a haze meter (“NDH-5000W” available fromNIPPON DENSHOKU INDUSTRIES CO., LTD.) in accordance with JIS K7136. Thehaze was measured under a condition in which the surface having thestructure with the recesses and protrusions was on a side of an opticalreceiver.

Transmission Image Clarity

Measurement was performed using a mapping measuring instrument (“ICM-1T”available from Suga Test Instruments Co., Ltd.) in accordance with JISK7105 under a condition in which the anti-glare film is installed, andthus the film-forming direction of the anti-glare film and the combtooth direction of the optical comb were parallel with each other. Theoptical comb width was set to 0.5 mm.

60-Degree Gloss

Measurement was performed at an angle of 60° using a gloss meter(“IG-320” available from Horiba, Ltd.) in accordance with JIS K7105.

Standard Deviation of Luminance Distribution of Display (Sparkle Value)

As the display device 16, a smartphone (“Galaxy S4” available fromSamsung Electronics Co., Ltd.) was used, and each of the sampleanti-glare films was attached on the surface of the display 16 a thereofby an optical clear adhesive. Note that, the display 16 a of thesmartphone has a resolution of 441 ppi. Further, the sparkle measurementapparatus 10 available from Komatsu NTC Ltd. was used, and a standarddeviation (a sparkle value) of luminance distribution of the display 16a through each of the sample anti-glare films was measured. At the timeof the measurement, at least one of an exposure time of the imagingdevice 12 or luminance of all the pixels of the display 16 a wasadjusted, and thus image data relating to a gray scale image with 8-bitgradation display and an average luminance of 170 tones was obtained.

Now, the measurement results with respect to the items described aboveare shown in Table 1.

TABLE 1 Example Example Example Example Comparative ComparativeComparative Comparative Comparative 1 2 3 4 Example 1 Example 2 Example3 Example 4 Example 5 Haze (%) 43.8 31.4 49.8 45.5 31.2 36.7 48.7 48.636.9 Transmissive 4.5 22.6 59.8 2.9 29.1 36.7 27 63.5 81.4 clarity (%)60-Degree 12 20 30 11 50 52 65 19.5 36 gloss (%) Sparkle 8.2 9.5 7.4 7.910.9 9.3 7.7 6.6 7.3 value

As shown in Table 1, with the phase separation method based on thematerials and the manufacturing conditions in Examples 1 to 3 and thefine particle dispersion method based on the materials and themanufacturing conditions in Example 4, the anti-glare films satisfyingthe above-mentioned conditions (the sparkle value falling within a rangeof from 6 to 10, the specular gloss of 30% or less, the transmissionimage clarity of 60% or less, the haze value of 50% or less) were ableto be obtained.

That is, it was found out that the recesses and protrusions satisfyingthe above-mentioned conditions were able to be formed on the surface ofthe anti-glare film 1 by setting kinds of phase separation materials tobe combined, a heating temperature for composition in a drying process,a flow rate of a drying air caused to blow against the composition, or alinear speed as in Examples 1 to 3.

Further, it was found out that the anti-glare film 1 satisfying theabove-mentioned conditions was able to be formed in the followingmanner. That is, fine particles to be dispersed in the matrix resin wereselected. Thus, a difference of refractive indexes of the fine particlesand the matrix resin was set to a value falling within a range from 0 to0.07, and the ratio G2/G1 of the weight G1 of the matrix resin to thetotal weight G2 of the plurality of fine particles included in theanti-glare layer falls within a range from 0.02 to 0.15. Then,manufacturing was performed under the manufacturing conditions providedin Example 4. That is, the fine particle dispersion method in Example 4,the following matter is conceivable. That is, materials were selected,and thus a repulsive interaction between the fine particles, and a resinor solvent other than the fine particles was strong when forming theanti-glare layer 3. Consequently, suitable aggregation of the fineparticles was caused, and a distribution structure of steep recesses andprotrusions with high number density was able to be formed on theanti-glare layer 3.

In contrast, by the fine particle dispersion method based on the rawmaterials and the manufacturing conditions in Comparative Examples 1 to3, the anti-glare film satisfying the above-mentioned conditions was notable to be manufactured. That is, in Comparative Examples 1 and 2, adifference in refractive indexes of the fine particles and the matrixresin was greater than 0.07. In Comparative Example 3, the ratio G2/G1of the weight G1 of the matrix resin to the total weight G2 of theplurality of fine particles included in the anti-glare layer was outsidea range from 0.02 to 0.15.

Further, the recesses and protrusions controlled statistically were notable to be formed on the anti-glare film by the transfer molding methodbased on the raw materials and the manufacturing conditions inComparative Examples 4 and 5, unlike the phase separation method as in,for example, Examples 1 to 3. Thus, the anti-glare film satisfying theabove-mentioned conditions was not able to be manufactured.

The present invention is not limited to the above-mentioned embodiments,and change, addition, or elimination may be made to the configurationsand the methods without departing from the gist of the presentinvention. For example, the fine particles in the second embodiment maybe dispersed in the matrix resin of the anti-glare layer 3 in the firstembodiment or the third embodiment.

REFERENCE SIGNS LIST

-   -   1 Anti-glare film    -   3 Anti-glare layer    -   16 a Display

The invention claimed is:
 1. An anti-glare film attached on a surface ofa display, the anti-glare film comprising an anti-glare layer, whereinthe anti-glare layer is set to have a sparkle value falling within arange from 6 to 10, a value of specular gloss of 30% or less, a value oftransmission image clarity of 34.1% or less, and a haze value of 50% orless, wherein the sparkle value is defined based on a value of astandard deviation of luminance distribution of the display under astate in which the anti-glare film is attached on the surface of thedisplay, wherein the specular gloss is measured with 60-degree speculargloss, wherein the transmission image clarity has an optical comb of 0.5mm, wherein the anti-glare layer includes a matrix resin and a pluralityof inorganic fine particles dispersed in the matrix resin, the inorganicfine particles having an average particle diameter that is a valuefalling within a range from 0.5 μm to 5.0 μm, and wherein the inorganicfine particles form recesses and protrusions on a surface of theanti-glare layer, and no organic fine particles are included in theanti-glare layer.
 2. The anti-glare film according to claim 1, whereinthe anti-glare layer includes a plurality of resin components, and theanti-glare layer has a co-continuous phase structure formed by phaseseparation of the plurality of resin components.
 3. The anti-glare filmaccording to claim 1, wherein a difference of refractive indexes of theplurality of inorganic fine particles and the matrix resin falls withina range from 0 to 0.07.
 4. The anti-glare film according to claim 3,wherein a ratio G2/G1 of a weight G1 of the matrix resin of theanti-glare layer to a total weight G2 of the plurality of fine particlesincluded in the anti-glare layer is a value falling within a range from0.02 to 0.15.